The present invention relates generally to the field of computer processor power supply and, more particularly, to a system and method for improved processor voltage regulation.
Modern electronic computing systems, such as microprocessor systems, often include electronic circuitry organized into discrete logic groups. In many cases, one or more of these logic groups are not necessary for every operation. For the purposes of power reduction, some systems restrict power to these logic groups during periods of inactivity, a process sometimes referred to as “power gating”.
Power gating has been widely used in very large scale integration (VLSI) designs to reduce or eliminate standby leakage by cutting off the power supply to inactive or “standby” circuits. Current power gating techniques typically employ on-chip circuits as footer or header devices to connect/disconnect standby circuits from their power supplies. While the footer/header approaches allow for power gating individual logic groups, these approaches also suffer from significant drawbacks.
For example, the footer/header devices themselves consume valuable chip area, which either reduces the area available for other functions or requires larger chips. In some cases, design and/or operational requirements preclude larger chips, which means that the designer must sacrifice functionality to achieve gains in power supply control. Where functionality cannot be sacrificed, designers sometimes must use fewer footer/header devices than are truly necessary, which increases resistance and noise on the power distribution networks.
Additionally, most footer/header techniques must also double the chip's distributed power supply networks. That is, typical footer techniques require a “virtual ground” to be distributed in parallel with a true ground. Similarly, typical header techniques require a “virtual VDD,” distributed in parallel with VDD. In many cases, on-chip interconnect wires are limited in availability, which limits the options for distributing virtual ground and/or virtual VDD. This limited availability often compromises noise immunity and IR drop, especially on virtual ground networks. This, in turn, directly degrades circuit frequency and performance.
Further, typical power supply lines from the motherboard (or module substrate, to which the processor couples) are limited and/or insufficient in satisfying the power requirements of advanced processors. That is, multi-core and/or multi-function processors sometimes require individual power supplies for each core/function, in order to optimize power consumption and/or performance. Typical processor power supply techniques, including common header/footer approaches, cannot meet these power demands without unsatisfactory compromises in chip size and/or on-chip area.